.banner img{
    position: relative;
    left: 0;
    top: 0;
    min-width: 100%;
    height: 100%;
    width: 100%;
}

.col-md-3{
    margin-top: 45px;
}
.u{
    display: none !important;
}
.big:hover .u{
    display: block !important;
}